Gas turbine engines find applications in confined environments with relatively low circulation of ambient air, such as gas turbine engines that serve as auxiliary power units (APUs) in the tail sections of aircraft. Such gas turbine engines often have an integral eductor coupled to the exhaust of the gas turbine engine to induce rapid air flow for cooling purposes, drawing ambient air either from within or without their confines by means of suitable ductwork.
The housing for the eductor circumscribes at least a portion of the combustor section of the engine, thereby cooling the combustor housing. It is common to mount an air-cooled heat exchanger over the inlet for the eductor that circulates and cools engine lubrication oil.
For best air flow, it is important that the eductor induces relatively uniform air flow around its entire perimeter. Unfortunately, due to the sideward mounting of the eductor inlet coupled with the central mounting of the combustor housing, air flow tends to dominate along the length of the eductor proximate its inlet. Furthermore, since for reasons of convenience the positioning of the eductor inlet is also approximately top dead centre over the combustor housing, any leakage of engine oil from an engine oil heat exchanger placed over it may drip onto the combustor housing, thereby creating a possible fire hazard.